The sudden resignation of four underwriters at Ace has reignited rumours that former group president and chief executive John Charman will make a comeback.

In March, Charman unexpectedly left the Bermuda-based insurer following “differences over personnel matters”. Last week, his deputy Jack Gressier, marine underwriter of syndicate 2488, and three other underwriters resigned from Ace Global Markets.

Market sources are suggesting that Gressier will be setting up a new outfit within Lloyd's, concentrating on directors' and officers' insurance. It is thought Charman will be assisting the team.

A spokeswoman for Ace confirmed a number of staff had resigned for “personal reasons”.

But she said: “If they are looking to re-enter the market in an underwriting capacity, we would be surprised, considering their contractual restrictions on operating in the market, and we will enforce any contracting agreements they have with us.

“Ace has access to worldwide underwriting resources and will seek to recruit, where appropriate, underwriters within the group. It is not thought that the departure of a small number of underwriters in the group will have an impact.”

She added that Andrew Kendrick would remain the formal active underwriter for the syndicate.

Charman, who was previously deputy chairman of Lloyd's, sold his underwriting agency to Ace for £349m three years ago. Syndicate 2488 provides around 10% of the Lloyd's Market capacity.